There have been conventionally known a semiconductor device including a nitride-based semiconductor layer and a method for manufacturing the semiconductor device.
Patent Literature 1 discloses a semiconductor device (HJFET: Heterojunction Field Effect Transistor) including a substrate made of SiC, a buffer layer formed on the substrate, a channel layer made of GaN and formed on the buffer layer, a barrier layer made of ALGaN and formed on the channel layer, and a source electrode, a drain electrode and a gate electrode formed at different positions on the barrier layer, respectively. Furthermore, in the semiconductor device disclosed in Patent Literature 1, a concave portion is provided in the barrier layer between the channel layer and the gate electrode.
The semiconductor device disclosed in Patent Literature 1 uses a conductive oxide (such as ZnInSnO) having a higher work function than that of Ni or the like normally used for a gate electrode and eliminates a two-dimensional electron gas layer below the gate electrode, thereby making it possible to obtain normally-off characteristics.
Citation List
Patent Literature
Patent Literature 1: Japanese Patent Laid-Open Publication No. 2007-149794